<?php
namespace library;
/*
 * 中文圆形印章类
 * @author lkk/lianq.net
 * @create on 10:03 2012-5-29
 * @example:
 * $seal = new circleSeal('你我他坐站走东西南北中',75,6,24,0,0,16,40);
 * $seal->doImg();
 */

class EsignContractSeal {
    private $sealString;  //印章字符
    private $strMaxLeng;  //最大字符长度
    private $sealRadius;  //印章半径
    private $rimWidth;   //边框厚度
    private $innerRadius;  //内圆半径
    private $startRadius;  //五角星半径
    private $startAngle;  //五角星倾斜角度
    private $backGround;  //印章颜色
    private $centerDot;   //圆心坐标
    private $img;      //图形资源句柄
    private $font;     //指定的字体
    private $fontSize;   //指定字体大小
    private $width;     //图片宽度
    private $height;    //图片高度
    private $points;    //五角星各点坐标
    private $charRadius;  //字符串半径
    private $charAngle;   //字符串倾斜角度
    private $spacing;    //字符间隔角度

    //构造方法
    public function __construct($str ='', $rad = 65, $rmwidth = 3, $strad = 24, $stang = 0, $crang = 0, $fsize = 16, $inrad =0){
        $this->sealString  = empty($str) ? '印章测试字符串' : $str;
        $this->strMaxLeng  = 15;
        $this->sealRadius  = $rad;
        $this->rimWidth   = $rmwidth;
        $this->startRadius = $strad;
        $this->startAngle  = $stang;
        $this->charAngle  = $crang;
        $this->centerDot  = array('x'=>$rad, 'y'=>$rad);
        $this->font     = dirname(__FILE__) .'/../seal.ttf';
        $this->fontSize   = $fsize;
        $this->innerRadius = $inrad;  //默认0,没有
        $this->spacing   = 1;
    }

    //创建图片资源
    private function createImg(){
        $this->width    = 2 * $this->sealRadius;
        $this->height    = 2 * $this->sealRadius;
        $this->img     = imagecreate($this->width, $this->height);
        imagecolorresolvealpha($this->img,255,255,255,127);
        $color = imagecolorallocate($this->img,255,255,255);
        imagefill($this->img,0,0,$color);
        $this->backGround  = imagecolorallocate($this->img,255,0,0);
    }

    //画印章边框
    private function drawRim(){
        for($i=0;$i<$this->rimWidth;$i++){
            imagearc($this->img,$this->centerDot['x'],$this->centerDot['y'],$this->width - $i,$this->height - $i,0,360,$this->backGround);
        }
    }

    //画内圆
    private function drawInnerCircle(){
        imagearc($this->img,$this->centerDot['x'],$this->centerDot['y'],2*$this->innerRadius,2*$this->innerRadius,0,360,$this->backGround);
    }

    //画字符串
    private function drawString(){
        //编码处理
        $charset = mb_detect_encoding($this->sealString);
        if($charset != 'UTF-8'){
            $this->sealString = mb_convert_encoding($this->sealString, 'UTF-8', 'GBK');
        }
        //相关计量
        $this->charRadius = $this->sealRadius - $this->rimWidth - $this->fontSize; //字符串半径
        $leng  = mb_strlen($this->sealString,'utf8'); //字符串长度
        if($leng > $this->strMaxLeng) $leng = $this->strMaxLeng;
        $avgAngle  = 360 / ($this->strMaxLeng);  //平均字符倾斜度

        //拆分并写入字符串
        $words = array(); //字符数组
        for($i=0;$i<$leng;$i++){
            $words[] = mb_substr($this->sealString,$i,1,'utf8');
            $r = 630 + $this->charAngle + $avgAngle*($i - $leng/2) + $this->spacing*($i-1);   //坐标角度
            $R = 720 - $this->charAngle + $avgAngle*($leng-2*$i-1)/2 + $this->spacing*(1-$i);  //字符角度
            $x = $this->centerDot['x'] + $this->charRadius * cos(deg2rad($r)); //字符的x坐标
            $y = $this->centerDot['y'] + $this->charRadius * sin(deg2rad($r)); //字符的y坐标
            imagettftext($this->img, $this->fontSize, $R, $x, $y, $this->backGround, $this->font, $words[$i]);
        }
    }

    //画五角星
    private function drawStart(){
        $ang_out = 18 + $this->startAngle;
        $ang_in = 56 + $this->startAngle;
        $rad_out = $this->startRadius;
        $rad_in = $rad_out * 0.382;
        for($i=0;$i<5;$i++){
            //五个顶点坐标
            $this->points[] = $rad_out * cos(2*M_PI/5*$i - deg2rad($ang_out)) + $this->centerDot['x'];
            $this->points[] = $rad_out * sin(2*M_PI/5*$i - deg2rad($ang_out)) + $this->centerDot['y'];

            //内凹的点坐标
            $this->points[] = $rad_in * cos(2*M_PI/5*($i+1) - deg2rad($ang_in)) + $this->centerDot['x'];
            $this->points[] = $rad_in * sin(2*M_PI/5*($i+1) - deg2rad($ang_in)) + $this->centerDot['y'];
        }
        imagefilledpolygon($this->img, $this->points, 10, $this->backGround);
    }

    //输出
    private function outPut( $filename ){
        //header('Content-type:image/png');
        imagepng( $this->img, $filename );
        imagedestroy($this->img);
    }

    //对外生成
    public function doImg( $filename ){
        $this->createImg();
        $this->drawRim();
        $this->drawInnerCircle();
        $this->drawString();
        $this->drawStart();
        $this->outPut( $filename );
    }
}